Carton structure



March 1962 R. K. GALLOWAY 3,024,961

CARTON STRUCTURE Filed Feb. 24, 1959 'l K {I v 36 :i ii I I I 7 52 INVENTOR I I E :3 ROBERT K. GALLOWAY f YMI "&

ATTORNEY United States atent Ofiice 3,024,961 CARTON STRUCTURE Robert K. Galloway, Hoopeston, 111., assignor to FMC Corporation, a corporation of Delaware Filed Feb. 24, 1950, Ser. No. 795,003 1 Claim. (Cl. 229-43) Cartons commonly employed in the packaging industry are made from paper stock possessed of resiliency to such an extent that when closure flaps thereof are folded to their closed positions, they tend to spring back toward their open positions. This frequently causes one or more of the walls of a carton to bulge outward, particularly in the case of cartons whose end closure flaps are locked in their closed relation by a tab on one flap inserted through a slit in an opposed, underlying flap. Such bulging of one or both closed ends of a carton of this type imparts several undesirable characteristics to the carton, among which are an unattractive appearance, lessened ability to resist crushing, and impaired protection for the commodity within the carton from both contamination and variation of its moisture content.

It has become common practice to overwrap such cartons, i.e., to wrap each filled and closed carton individually with a wrapper imprinted so as to function as a label appropriate to the contents of the carton. Such procedure, however, while producing an eflicient and attractive package, is expensive and entails additional machinery.

It is, therefore, an object of the present invention to rovide an improved carton construction.

Another object is to provide an improved carton structure particularly adaptable to cartons of the locking tab and slit type.

Another object is to provide a carton structure having high compressive strength.

Another object is to provide a carton structure that affords adequate protection for its contents Without being overwrapped.

Another object is to provide a carton having end closure flaps adapted to be held closed by one or more locking tabs on one flap inserted into slots in an opposed flap, which car-ton is so constructed that the inter-engaged flaps are prevented from bulging outward.

Another object is to provide an improvement in the construction of cartons of well known type which is highly effective in imparting to the carton the above mentioned characteristics, and yet which are so simple that it can be added to the carton at high speed, with simple and inexpensive equipment and as a part of the operation of closing the end flaps or as a step coincident thereto.

These and other objects and advantages will become apparent from the following description and the accompanying drawings, in which:

FIG. 1 is a perspective of a carton of the locking tab md slot type prior to its being filled and closed, and prior to its being modified in accordance with the principles of the present invention.

MG. 2 is a perspective of the completed carton, to which the improved structure of the present invention has been imparted.

FIG. 3 is a section taken on line 33 of FIG. 2 and illustrates the improved carton structures of the present invention.

FIG. 4 is an enlarged fragmentary section illustrating the portion of the carton shown in the upper left hand corner of FIG. 3.

The carton C illustrated in FIG. 1 is of a type commonly employed in the frozen food industry in marketing frozen pics. The improved carton structure of the present invention is adapted for, but is not necessarily limited to, use in cartons of this type.

The carton C of FIG. 1 comprises a top panel 10, a bottom panel 12, a front panel 14 and a rear panel 16. Front end flaps 18 are attached to the opposite ends of the front panel 14, rear end flaps 20 are attached to the opposite ends of the rear panel 16, top end flaps 22 are attached to the opposite ends of the top panel 10, and bottom end flaps 24 are attached to the opposite ends of the bottom panel 12. The top end flaps 22 are provided with locking tabs 26 which project from the free edges thereof, and tab receiving slits 28 are provided in the bottom end flaps 24. The procedure that is followed in closing each end of the carton consists of folding inward the front and rear end flaps 18 and 20 at that end and then folding the associated top and bottom end flaps 22 and 24 into overlapping relation and inserting the locking tabs 26 into and through the slits 28. When the end flaps 18 and 20 are thus folded, each is swung about a hinge line 30 at the inner end of the flap where it joins the front or rear wall 14 or 16, as the case might be. The top and bottom end flaps 22 and 24 are swung about hinge lines 32 and 34 similarly situated with relation to the respective flaps 22 and 24. Accurate folding at the hinge lines 30, 32 and 34 is facilitated by scoring the carton stock along each of the hinge lines.

Although the carton thus far described, and folded as above explained, is typical of cartons extensively used for packaging frozen food and other commodities, it is characterized by certain disadvantages caused by the inherent resilience of the carton stock. The reason for this is that after the carton flaps 18, 20, 22 and 24 have been folded to carton closing arrangement, they are urged by the resilience of the carton material to return to their open positions. Although the above mentioned scoring of the carton stock along the hinge lines of the closing flaps materially lessens the force with which the closed flaps are urged back to their open positions it is found that so much resilience remains that the closed and interlocked top and bottom flaps 22 and 24 usually assume an arcuate configuration, causing the end wall 36 that is formed by these flaps to bulge outward. This creates a condition conducive to development of the hereinabove mentioned undesirable characteristics common to paper cartons.

The present invention prevents such outward bulging of a carton wall in response to the inherent resilience of the carton stock that urges a folded wall to return to planar alignment with the top or bottom panel to which it is hingedly connected. In the case of the end Wall 36 (FIGS. 2, 3 and 4) that is formed by the overlapping and interlocking flaps 22 and 24 this is accomplished by pushing the wall 36 inwardly of the carton to a position wherein the major portion of the wall 36 is spaced inward from the plane that includes the edges of the top and bottom panels 10 and 12; i.e., the plane that includes the hinge lines 32 and 34 of the flaps 22 and 24. The extent to which the flaps 22 and 24 are spaced inward from this plane is substantial-preferab1y it is approximately equal to or slightly greater than the thickness of the carton stock, as best shown in FIG. 4. As such inward pushing of the wall 36 occurs, each flap 22, 24 is bent approximately about a crease line 38 spaced the mentioned distance from the associated hinge line 32 or 34, as the case might be, and the narrow strips 40 (see FIG. 4) of the flaps 22 and 24 lying between the crease line 38 of the fiap 22 and the hinge line 32, and between the crease line 38 of the flap 24 .and the hinge line 34, are folded back tightly against the inner surfaces of the top and bottom panels 10 and 12, respectively. Thus, the carton stock is reversely folded back upon itself in a manner forming outwardly projecting beads 50 and 52 at the hinge lines of the flaps 22 and 24, respectively. Each of these beads 50, 52 is two-ply, one ply consisting of the end region of the top or bottom panel 10 or 12, as the 3 case might be, and the other ply being the narrow strip 40 of the end flap 22 or 24. The crease line 38 of the flap 22 is .at the base of the head 50, and the crease line 38 of the fiap 24 is at the base of the bead 52.

Since the beads 50 and 52 project outward from the end flaps 22 and 24 to the hinge lines 32 or 34 thereof, they cooperate with the remainder of the assembled wall 36 to define a concave, or channel-shaped structure lying within the confines of the top and bottom carton panels and 12, respectively. The concavity of the wall is made more pronounced by imparting a slight inwardly curved configuration to the web portion of the channelshaped structure. Within this web portion, both flaps 22 and 24 possess the same degree of curvature so that they make surface contact with each other throughout substantially the entire extent of their overlapping regions.

Due to the sharp creasing of the carton stock in forming the 'beads 50 and 52 and the creases 38, the strains within the carton stock which otherwise would tend to bow the end flaps outward have been relieved, and the end flaps will normally remain in their inwardly offset, inwardly curved arrangement. An important advantage that derives from this feature is that if the top and bottom panels 10 and 12 of the carton C of the present invention are subjected to forces tending to crush the cart-on in the region adjacent one of its ends, the flaps 22 and 24 will be urged inwardly, rather than outwardly, because of the concave channel shape of the carton end. However, the flaps 22 and 24 cannot readily turn farther inward, because they bear at their ends against the front and rear end flaps 18 and 20, and, probably, between their ends against the contents of the carton. Therefore, the ability of the carton to resist crushing is materially increased by the carbon structure of the present invention.

Both the actual location of the wall 36 with the confines of the space between the top and bottom panels 10 and 12, and the inward curvature of the wall contribute to the capability of the closure flaps 22 and 24 comprising the wall to prevent gapping at the ends of the front and back walls 14 and 16, respectively. This is because the inwardly offset and inwardly curved flaps 22 and 24 bear firmly against the inwardly folded front and rear end flaps 18 and 20, respectively. Therefore, when the flaps 22 and 24 have been shaped in accordance with the present invention they do not leave the gaps at ends of the front and rear canton walls 14 and 16 that usually are present in similar cartons to which the invention has not been applied. Moreover, since the two flaps 22 and 24 make surface contact with each other throughout substantially the entire extent of their overlapping regions, as above explained, no gap is left between the distal, or free edge 42 (FIGS. 1 and 2) of the overlying flap 22 and the outer surface or" the underlying flap 24, as has been the case with car-tons whose closure flaps are permitted to bulge outward.

Consequently, another important advantage derived from applying the present invention to the carton C is that the carton C is thereby made almost, if not quite, hermetically sealed, and thus placed in a condition wherein it provides eflicient protection for its contents, both against contamination and against variation of moisture content. For this reason the carton structure of the present invention is particularly advantageous when applied to cartons having a surface coating that makes them so impervious to moisture penetration that they provide maximum protection for their contents without overwrapping.

Another feature of the present invention that should be observed is that the beads 56 and 52 are formed by deforming only the flaps 22 and 24, and without altering any part of the top and bottom panels 10 and 12 of the carton. Consequently, the above explained advantages are derived without changing the perfectly fiat characteristics of the top and bottom panels 10 and 12, With the result that application of the present invention to the cartons C does not interfere with their capability of being stacked one on top of another, nor does it cause a stack of a number of the carton-s to occupy any more space. Thus, no change is required in the shipping containers in which wholesale quantities of the cartons are stored and shipped.

While the improved carton structure of the present invention is disclosed "herein in connection with a carton of a specific type, it should be noted that the structure is equally applicable to cartons of other types without departing from the spirit of the invention as defined in the appended claim.

The invention having thus been described, what is claimed and desired to be secured by Letters Patent is:

A rectangular carton comprising two parallel spaced rectangular panels and side walls extending therebetween, each of said panels and side walls having closure flaps hinged at the ends thereof, the flaps on said panels overlying the flaps on said side Walls, said panel flaps having overlapping and interlocking relation, said panel flaps only having a narrow portion folded inwardly about a scored hinge line to be contiguous with the inner surface of the associated panel, each of said panel flaps having a reverse fold of substantially joining said narrow inwardly folded flap portion to the remainder of the flap, said remainders of the flaps forming end walls of the carton, said narrow inwardly folded flap portions and the contiguous panel portions forming narrow beads, said beads and the associated end wall forming an open ended channel that extends entirely across the end of the carton, said end walls each extending in a shallow curve between the associated beads with the outer face of each end wall being concave, application of a crushing force to the carton panels tending to deflect said end walls inwardly against the contents of the carton.

References Cited in the file of this patent UNITED STATES PATENTS 1,897,692 De Voe Feb. 14, 1933 2,337,198 Holy Dec. 21, 1943 2,415,173 Hulbert Feb. 4, 1947 2,444,895 Ringler July 6, 1948 2,591,882 Shirley Apr. 8, 19'52 

